Handling Standard XML Schemas | ||||||||
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< < | An XML Schema document is an XML document that defines a set of XML tag names that can be used to describe something in XML. Such documents typically end with the file extension .xsd . A W3C standard defines the XML language used to define the specialized tag names. An IVOA standard XML schema is one that has been defined in an IVOA specification document that goes through the IVOA standardization process. Standard schemas are most commonly used in the IVOA in support of Registries, but they are also used in other areas. | |||||||
> > | An XML Schema document is an XML document that defines a set of XML tag names that can be used to describe something in XML. Such documents typically end with the file extension .xsd . A W3C standard defines the XML language used to define the specialized tag names. | |||||||
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> > | An IVOA standard XML schema is one that has been defined in an IVOA specification document that goes through the IVOA standardization process. Standard schemas are most commonly used in the IVOA in support of Registries, but they are also used in other areas. All standard XML schema documents are available for download via http://ivoa.net/xml . | |||||||
Naming ConventionsNamespaceA schema is identified via its namespace URI, which is globally unique. It is assigned within the schema (.xsd) document. A namespace URI for an IVOA standard schema must comply with the following convention: http://ivoa.net/xml/shortname/vversion where shortname is a short name identifying the schema and version is the version of the schema. For example, VOResource namespace URI ishttp://ivoa.net/xml/VOResource/v1.0 | ||||||||
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> > | Typically, versions are kept to a two field format, N.N, (e.g. "0.1", "1.0", or "2.1").
Schema filenamesThe official name for a schema file name must have the following form: shortname-vversion.xsd where shortname and version correspond to the same fields in the namespace. For example, the VOResource schema is stored in a filename on the IVOA web server asVOResource-v1.0.xsd
Publishing the XML schemas on the IVOA web siteWhere schema files are accessedIn the IVOA, a standard schema is accessible via 2 different URLs. The first is a URL that matches the schema namespace (as defined above). The second is through a similar URL of the following form: http://ivoa.net/xml/shortname/filename where filename is the name mandated above. For example, the VOResource schema document can be downloaded through either of the following URLs:http://ivoa.net/xml/VOResource/v1.0 http://ivoa.net/xml/VOResource/VOResource-v1.0.xsd
Both return the same document.
The first URL is convenient for XML-aware software. Software can tell if an XML document is correct by making sure it complies with the rules set out in the XML Schema document. The XML document can, optionally, say where to get the schema, but some software, if it isn't told where to find it, will try using the namespace URI as URL for the schema document itself.
The second URL tends to be convenient for human users. A user can access the directory at http://ivoa.net/xml/VOResource/ and browse the various versions there; if he wants to save the schema locally, he can click on
it and his browser will typically ask him to save it with the name VOResource-v1.0.xsd . (The other URL might result in a local filename of v1.0 , which is less convenient.)
When schema files are submitted or updatedThere are typically three types of occasions when a schema file needs to be submitted to the web site and published.
How a new or updated schema document is submittedWorking group chairs (or their explicit desginate) are responsible for submitting schema documents associated with their working group activities. There are two ways to submit a schema document for publishing on the web site:
Installing a schema documentThe IVOA web site exists as a collection of directories and files on the file system all contained under a single root directory. In this section we refer to this root directory as<webroot>: .
Upon receipt of a submitted schema document, the following steps can be followed to publish:
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Handling Standard XML SchemasAn XML Schema document is an XML document that defines a set of XML tag names that can be used to describe something in XML. Such documents typically end with the file extension.xsd . A W3C standard defines the XML language used to define the specialized tag names. An IVOA standard XML schema is one that has been defined in an IVOA specification document that goes through the IVOA standardization process. Standard schemas are most commonly used in the IVOA in support of Registries, but they are also used in other areas.
Naming ConventionsNamespaceA schema is identified via its namespace URI, which is globally unique. It is assigned within the schema (.xsd) document. A namespace URI for an IVOA standard schema must comply with the following convention: http://ivoa.net/xml/shortname/vversion where shortname is a short name identifying the schema and version is the version of the schema. For example, VOResource namespace URI ishttp://ivoa.net/xml/VOResource/v1.0
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